singleton said:
Hey,
Well basically I've been skimming over lots of different multiverse theories and as I don't have a science background (total layman) my question is basically can these two theories co-exist or do they not leave room for each other in the way that they fit in?
As far as I understand myself, string theory (in as far as it is already a theory, and not just some suggestions of how one might one day obtain a theory) is a specific (kind of) quantum theory. A specific *interpretation* (that means, how to give ontological and philosophical meaning to the elements of the formal theory) of quantum theory is the so-called "many-worlds interpretation" (of which there exist different flavors) ; there are other interpretations of quantum theory too, but they all have something odd to themselves and none is 100% satisfactory ; hence people talk about the "measurement problem" of quantum theory.
As such, one can look upon string theory (which is probably a quantum theory) within the interpretation of the MWI if one likes to.
I don't even know what MWI point of view that I mean (as I don't know the difference between Everett and Deutch if any and where Tegmark fits in).
Everett is the inventor of the MWI view on quantum theory (1957). Tegmark often explains it (Scientific American etc...) and Deutch is a fervent defender of MWI. But they all talk about the same basic idea.
Now, a word of caution. Although I consider myself also an MWI proponent, be aware that all this is hypothetical (contrary to some annoying claims by Deutch that he experimentally *proved* MWI). In order to understand the appeal of MWI (which is, on a philosophical level, quite bizarre), one needs to understand the mathematics of quantum theory a bit. Then one will realize that the mathematical formulation of quantum theory is really very "MWI" inspired, and as such (this is the reason why I like it), the MWI interpretation is what is most literally suggested by the way quantum theory is usually mathematically formulated.
But then, it is such a weird idea that many people cannot accept this, and - in different ways - they say that somehow, the mathematics of quantum theory is not a DESCRIPTION of what is happening, but just a TOOL to help us calculate things. That was also Einstein's viewpoint, and even Bohr's. However, when one then asks what IS then a good description (if it is not given by quantum mechanics), then things start out to get tough. So, although you can easily say that quantum theory is just a tool and not a description, it is not easy to find another genuine description that gives (about) the same results as quantum theory, but doesn't contain the weirdness of MWI. There have been attempts to do this, but all of them also contain something that is not really satisfactory. The different proponents then argue whether THEIR difficulty is not much more acceptable than the MWI weirdness. As all these different views are NOT DISTINGUISHABLE (most of the time) EXPERIMENTALLY, the different viewpoints are strictly speaking not scientific questions. On the other hand, talking about what a formalism "physically means" is, in my opinion, part of the larger scope of what science is about. But it is its "meta-scientific" part, not its hard-core science part.